Okay, I had actually already started writing this when I saw this thread, and now I'm done. I've never written an analysis before, so there's a very high chance that it's flawed. It's also about Spinarak, so that may be a flaw in itself... haha, but I think I brought out the best of the little bug.
SPINARAK! Aaaah!
name:
Swarmer
move1: Agility
move2: Substitute
move3: Signal Beam
move4: Psychic
item: Petaya Berry
ability: Swarm
nature: Modest
evs: 196 HP/ 116 Spd/ 196 S.Atk
[Set comments]
Trying to find a niche for this little spider is hard, but this is one possible use. Find some time to get an Agility in and then Substitute down to Petaya range, which is also when Swarm will activate. Signal Beam is powered up by both Swarm and the Petaya Berry to get a good hit on many things. This set can OHKO the likes of Abra, Gastly, Onix, and Rhyhorn, as well as many fragile sweepers-- as long as you can find some way to get the Agility in, which will put you at 22 Speed.
name:
Choice-Revenge
move1: Poison Jab
move2: Sucker Punch
move3: Shadow Sneak
move4: Pursuit
item: Choice Band
ability: Insomnia
nature: Adamant
evs: 116 HP/ 196 Atk/ 196 Spd
[Set Comments]
The type coverage is somwhat redundant, but the moves will make him a decent revenge killer. This set can OHKO Misdreavus with either Sucker Punch or Pursuit if you catch her switching. Poison Jab is the primary STAB and will OHKO the likes of Murkrow... as long as he doesn't kill you first. By the way, his strongest physical bug move is Pin Missile, so ignore bug moves on this set and stick with Insomnia for an ability.
[Other Options]
Sucker Punch can be used on the Swarm set in place of Psychic to stop priority moves and Choice Scarfers, and it would yeild switching your HP EV's into maximizing attack. Ariados likes to Baton Pass, so Spinarak may be able to mimic that, but he has nothing to pass other than Agility, a pathetic substitute, and Spider Web, so it is not the most effective option. You could try him with a Special set that included Giga Drain and Sludge Bomb (maybe even make him a sunnybeamer), but he doesn't hit very hard without the Swarm/Petaya combo because of his 40 base Special Attack. He also gets Toxic Spikes.
[Illegal Moves]
Of note, Toxic Spikes + Baton Pass cannot be used together.
[EV's]
Because all of his stats end in zeroes, he can add a total of 8 points to his stats, which is kind of nice because he needs as many as possible. Max out one or both of your attacking stats and then put some into HP or Speed.
The Swarm set hits 11 speed, but if you don't feel good enough about the number 22, you can add another point to hit 12 (24 after Agility) and take some out of HP.
[Opinion]
Although Spinarak is one of only two Swarmers in little cup, it is unlikely that he will ever see too much widespread use. Still, he can hit surprisingly hard with a STABbed, Swarmed, +1 S.Atk Signal Beam. Similarly, although base 60 Attack isn't overwhelming by any means, his physical movepool is interesting and works fairly well.
[Counters]
Spinarak's problem is that he doesn't like things faster than he is, but he only has base 30 speed. So things with Scarves or priority moves that don't fear his base 40 defenses across the board will take him out. Special incarnations can't touch Misdreavus and physical Spinaraks have trouble with Onix and Rhyhorn. All Spinaraks have problems with fire-types, flying-types, and steel-types. Stealth Rock is also hurtful. Sandstorm and Hail will beat up the Swarm set, too.